U.S. Pat. No. 4,742,593 to Kallenbach depicts an exemplary “suction-side” type of hydraulic automatic pool cleaner (APC). The cleaner includes an operating head, or body, together with a foot functioning as a bearing surface (among other things). Typically connected to the foot is a disc, examples of which are illustrated in U.S. Pat. No. 5,465,443 to Rice, et al. An outlet of the body normally communicates with a hose and thence to the inlet (i.e. the “suction side”) of a pump of a water-recirculation system associated with a swimming pool. Operation of the pump tends to evacuate the body, drawing debris-laden water from the pool into the body and thereafter into the hose. Located either within the body or remote therefrom, a mechanical filter typically strains the water before it encounters the inlet of the pump.
Present within the body is a valve designed periodically to interrupt the flow of water through the body. This periodic interruption of flow produces a water-hammer effect resulting in movement of the cleaner about the pool. Alternatively, flow through the body may operate a turbine or other device designed to drive wheels of a cleaner.
U.S. Pat. No. 5,720,068 to Clark, et al. illustrates an exemplary “pressure-side” hydraulic APC. It too comprises a body communicating via a hose with a pump, albeit with the outlet (i.e. “pressure side”) of the pump rather than with its inlet. Pressurized water (jets) exiting the body functions to move the cleaner within the pool; exploiting the Venturi principle, it also creates a low pressure region within the body for drawing pool water therein.
Both suction-side and pressure-side APCs are configured to move when connected to an operating pump. In other words, the relevant motive force creator (water-interruption valve, turbine, jet, etc.) is designed, conventionally, to be operational whenever the APC is communicating with the pump and the pump is activated. At times, though, it may be advantageous to cease movement of a cleaner without necessarily disconnecting it from or deactivating the pump. For example, if activities are occurring in one area of a pool, disabling a cleaner so as to prevent its movement into that area could be beneficial. As another example, if the pump is connected as well to some other object, reducing the force required to move the cleaner permits more pump force to be available for application to the other object.